Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 564 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) ironing the paper (d) dipping the cotton bud
2. 2.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
3. 3.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we measure it (c) we keep it the same
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we measure it (c) we change it
7. 7.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
8. 8.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) only an adult (d) whoever is fastest
9. 9.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing turns green (d) writing stays faint
10. 10.🍋 Which of these steps is a job a child can do? (a) writing the message (b) putting the iron away (c) plugging in the iron (d) ironing the paper
11. 11.🔍 Which is the odd one out? (a) cutting the lemon (b) ironing the paper (c) plugging in the iron (d) dipping the cotton bud
12. 12.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) writing the message (d) ironing the paper
13. 13.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
14. 14.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) dipping the cotton bud (d) ironing the paper
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the ironing time (c) how dark the writing is
16. 16.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
17. 17.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
18. 18.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
19. 19.📘 The browning of lemon juice with heat is a ___ change. (a) musical (b) magnetic (c) physical (d) chemical
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) how dark the writing is (c) the same paper (d) the kind of juice
21. 21.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
23. 23.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
24. 24.True or false: a magnet is not needed for the secret lemon message. (a) False (b) True
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a small bowl (c) lemon juice (d) turmeric powder
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the same paper (c) how dark the writing is (d) the same cotton bud
27. 27.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) dipping the cotton bud (d) ironing the paper
28. 28.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
29. 29.True or false: plugging in the iron is a job for an adult. (a) False (b) True
30. 30.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
31. 31.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
32. 32.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) brown (d) blue
33. 33.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) lemon juice (d) a magnet
34. 34.True or false: yeast is needed for the secret lemon message. (a) False (b) True
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we measure it (c) we change it
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
37. 37.True or false: ironing the paper is a job a child can do. (a) True (b) False
38. 38.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we change it (c) we measure it
40. 40.🍋 Which of these steps is a job for an adult? (a) reading the message (b) plugging in the iron (c) letting the paper dry (d) dipping the cotton bud

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